Need Objective advice on a Ex-best friend situation?

I haven’t been on this site in a while, I asked a question before about my ex best friend because she was trying to make amends for her attitude, but it didnt work out. She was making excuses for her uncouth and disgusting comments on my relationship and my choices in life. And, I couldn’t get pass her unwillingness to take responsibility, so I kindly told her we are at different points in my life, and maybe we can revisit our friendship years down the line. She took is well (so I thought). 2 months later, I felt the urge to contact her just to see if there is a chance to rekindle our friendship, and she completely dismissed me. Saying things that I wasn’t a good friend, I should have known she was going through tough times that’s why she acting the way she acting, she doesn’t want to talk to me ever again unless I was dying or something like that, etc. I told her she never takes responsibility for own actions, and I wished I never knew her (harsh, but honest).

After that conversation everything was fine, I went on with my life. Gain a ton of new friends, and now drama is happening. Unfortunately for me, me and my ex best friend have mutual friends in addition to she use to go to school with my boyfriend, so they also have mutual friends. She is going around the school making a sob story about me and my boyfriend being the bad guys and she’s the victim, which caused my boyfriend and I to lose a couple of friends who believed her.

I’m still friends with some of her friends and her mother on Facebook. I honestly don’t want the drama, but would it be childish of me to delete her mother and her friends? I’m cordial with these people, but I just don’t want them to use my Facebook as a mean of telling my ex best friend information about me.

Sorry for the long message, its just that I need objective opinions. What my friends are telling me is completely subjective and emotional, and I dont’ want to do anything in a haste.